Combustion engines in portable, handheld work apparatuses such as motor-driven chain saws, cutoff machines, brushcutters, blower devices or other handheld work apparatuses are predominantly equipped with a pull-rope starter to start the combustion engine manually. The pull-rope starter acts on the crankshaft of the combustion engine and rotates the crankshaft.
A fuel/air mixture (if the combustion engine is a two-stroke engine) also contains the oil which is necessary for operating a two-stroke engine and is fed to the combustion engine via an intake channel. The fuel/air mixture, which is drawn in, is compressed by a piston in a combustion chamber of the combustion engine and is ignited by a spark plug which is actuated by an ignition unit.
The fuel is fed to the intake channel via a fuel system which has a fuel channel which opens into the intake channel and via which the fuel quantity which is fed in flows. An electric fuel valve is arranged in the fuel channel, which fuel valve is open in its nonenergized (currentless) state and releases the fuel channel, and closes the fuel channel only when an operating voltage is applied, with the result that the fuel channel is shut off and no fuel can be drawn by suction into the intake channel.
An electronic control unit controls the fuel valve and the ignition, the electrical energy being made available by a generator which rotates with the crankshaft.
The fuel valve is a normally open valve and no electrical energy for closing the fuel valve is available before the combustion engine is started. For this reason, the fuel channel of the fuel system is first open. If the combustion engine is started, for example via a pull-rope starter, combustion air is drawn in by suction via the intake channel and fuel will also pass via the fuel paths, which are provided, into the intake channel because of the vacuum pressure which is produced as a result. An ignition spark is triggered at the spark plug and the fuel valve is actuated to meter in the desired fuel quantity only after the ignition generator, which is driven with the crankshaft, makes sufficient energy available.